a. Field of the Invention
The present invention relates to electrophysiological (EP) catheters. More particularly, the present invention relates to an irrigated EP catheter for use in ablation procedures, that includes a flexible manifold disposed between the shaft and electrode assembly of the catheter.
b. Background Art
It is known to use catheters to perform a variety of functions relating to diagnostic and therapeutic medical procedures. Electrophysiological (EP) catheters find particular application in cardiac electrophysiology studies and procedures, such as various cardiac diagnostic and/or ablation procedures. In ablation procedures, electrodes mounted or otherwise disposed at the distal end of the catheter may be used to deliver energy to the heart to ablate a site of cardiac tissue that causes, for example, an arrhythmia or abnormality in the heart rhythm.
Because ablation procedures may generate significant heat, which if not controlled can result in excessive tissue damage, such as, for example, steam pop, tissue charring, and the like, it is desirable to include a mechanism to irrigate the target area and the ablating electrode(s) with biocompatible fluids, such as, for example, saline solution. The use of irrigated catheters can also prevent the formation of soft thrombus and/or blood coagulation during ablation procedures.
Typically, there are three classes of irrigated catheters used in ablation procedures—open, closed, and external irrigated catheters. Closed irrigated catheters usually circulate a cooling fluid within the inner cavity or lumen disposed proximate the ablation electrode.
Open irrigated catheters typically deliver the cooling or irrigating fluid through irrigation ports or outlets to a surface of the ablation electrode. Open irrigated catheters use an inner cavity or lumen of the electrode to distribute saline solution, or other irrigating fluids known in the art, to one or more irrigation ports or outlets disposed within the electrode and between the inner cavity and outer surface of the electrode. Thus, the irrigating fluid flows through the irrigation ports onto the surface of the electrode. However, one drawback of this particular type of irrigated catheter is that the flow of the irrigating fluid through the electrode lowers the temperature of the electrode during operation, often making accurate monitoring and control of the ablative process more difficult.
External irrigated catheters provide one solution to this drawback. More particularly, rather than distributing irrigating fluid directly from the electrode of the catheter, as is done in open irrigated catheters, external irrigated catheters use a fluid manifold disposed between the catheter shaft and the electrode to distribute irrigation fluid from the catheter. More particularly, the manifold distributes irrigation fluid to the external surface of the electrode to cool the electrode and to also minimize the blood coagulation. Accordingly, it is known that external irrigated ablation catheters typically include, in part, a shaft having a proximal end and a distal end, and an electrode assembly disposed at the distal end of the shaft that is comprised of a proximal manifold portion and a distal electrode portion. Therefore, the manifold is disposed between and coupled to each of the distal end of the shaft and the proximal end of the electrode. In known systems, the manifold typically includes an inner cavity configured for fluid communication with an irrigation lumen in the shaft of the catheter. The manifold further includes a plurality of irrigation ports configured for fluid communication with the inner cavity to distribute irrigating fluid passing from the irrigation lumen, to the inner cavity, and then on to the surface of the ablation electrode and/or surrounding tissue.
These known arrangements, however, are not without their drawbacks. For instance, in ablation procedures, it is often desirable to create a deep lesion on the cardiac tissue. In order to do so, it is important to have adequate contact between the electrode of the catheter and the cardiac tissue being ablated. However, the manifold of typical external irrigated ablation catheters is usually formed of rigid plastic materials, such as, for example, polyetheretherketone (PEEK), having little to no flexibility. As such, optimal contact between the electrode and the cardiac tissue may not be achieved because the electrode assembly cannot be sufficiently deflected due to the rigidity of the manifold.
Another drawback lies in the distribution of the irrigating fluid from the manifold. In known arrangements, irrigating fluid is equally distributed from all of the irrigation ports disposed in the manifold regardless of the relative location of the irrigation port in relation to the site where the ablation function or operation is performed. Accordingly, fluid is distributed or expelled from the manifold to areas where irrigation is not needed, and thus, irrigating fluid is unnecessarily wasted.
Accordingly, there is a need for a catheter that will minimize and/or eliminate one or more of the above-identified deficiencies.